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By Earl F. Mathers

Few people would question that coal is king in the Campbell County, WY area. Other industries, such as oil production and ranching, also contribute significantly to the economic base, but coal mining and related industry development dominate. In recent years, Gillette has become the commercial hub of northeastern Wyoming. This development has been largely a response to the growth of the coal industry in Campbell County. Historically, Campbell County developed as a ranching area, a process that was aided by the passage of rail lines through the area, allowing early ranching interests to get their livestock to market. For decades, the Gillette-Campbell County area was predominantly a ranching area that experienced only incremental population growth.

Jan 1, 1994

By Po-Wei Tun, Kuen-Yuh Wu, Tso-Min Shih, Hsi-Chiang Fang

The purpose of this study is to investgate the coal dust explosion characteristics and to search for the prevention methods of the coal dust explosion as well as the propagation of the explosion flame of the middle-bearing coal formation in Taiwan by an open type coal dust explosion apparatus in laboratory. The coal samples were taken from the typical middle-bearing formations of the Sam-Ming,Tai-Ho and Lee-Fong coal mines The rock dusts, the free water mixture with coal dust samples and the interval clean out the coal dust in the testing chambers were applied for preventing the coal dust explosion and the propagation of the explosion flame.

Jan 1, 1993

By Z. M. Zavodni, M. K. McCarter

This paper identifies physical conditions responsible for past instability of the Main Hill area in Kennecott Copper Corporation's Bingham Canyon Mine, Bingham Canyon, Utah, and describes successful stabilization techniques employed in this slide zone. Geotechnical highlights of recent slides are presented, including monitoring, geological engineering data collection, hydrology, physical rock properties, and stability analyses. Local conditions responsible for slope movement in the Main Hill zone are: (1) high pore water pressure that causes a substantial decrease in real and effective material strengths; (2) continuous structural systems that allow sliding in the more competent rock zones; and (3) broad areas containing fractured, altered , and incompetent rock and soil- like materials. The failure mode is structurally controlled and involves a circular-type soil failure in the toe region initiated by excessive pore water pressure. A surface mapping method is presented which assigns rock mass quality on the basis of block size and rock substance strength. This site characterization technique has successfully predicted slide boundaries and failure modes; used in conjunction with laboratory determined shear strengths, it has provided basic input for calculating slope safety factors in the Main Hill slide zone.

Jan 1, 1977

By L. G. Sobral, J. E. Hoffman, T. J. Keefe, A. J. Monhemius, O&apos

The kinetics of electrodeposition of gold from dilute solutions of alkaline KAu(CN)2 at different gold and free cyanide concentrations on a gold rotating disk electrode were investigated by use of a steady-state linear potential scan technique. The design and performance of a laboratory electrowinning cell with a reticulated nickel cathode, operating in the flow-through mode, for the removal of low levels of gold ions from aqueous cyanide media is described. During the batch recirculation of oxygen-free gold cyanide solutions, the gold concentration was reduced from 10 ppm to <0.5 ppm with current efficiencies of up to 80%. The influence of solution flow rate through the cathode and of the pore size of the reticulated nickel foam is discussed. The removal of gold ions from solutions of low ionic strength was also investigated.

Jan 1, 1993

By M. C. Fuerstenau

With increased emphasis on controlled blasting, which is the first and least-costly stage of comminution, ore grindability and plant throughput can be increased by 5% to 10%, and energy savings of up to 10% appear possible. Crushing and grinding efficiencies are presented for ore blasted under regular and adjusted field conditions. An economic analysis of drilling and blasting through crushing and grinding is presented, suggesting that cost savings approaching 10% may be achieved

Jan 1, 1997

By Lars Olaf Höglund

MiMi has been set up to be i) visionary, ii) strategic and iii) long-term. The planning as well as the executive phases involves industry, academia and authorities in close co-operation. MiMi focuses on improved, economically efficient management of mining waste, a challenge that requires combined and integrated research efforts across discipline boundaries. The MiMi programme is financed by the Swedish Foundation for Strategic Environmental Research (MISTRA) with support from the mining industry. The first programme phase covers the period 1997 - 2000, with intentions for additional phases. Planning, experience and results from the first programme period are highlighted. INTRODUCTION Most of the mining activities in Sweden takes place in the No

Jan 1, 2000

By T. Zoltai

Asbestos is a generic term for industrially useful fibers recovered from exploitable deposits of the asbestiform varieties of five silicate minerals: chrysotile, anthophyl-lite, actinolite-tremolite, cummingtorute-grunerite, and rie-beekite. Asbestos and asbestiform fibers of some other minerals are known to be carcinogenic. Minerals crystallized in the asbestiform habit-are characterized by unique properties (morphology, strength and flexibility, physical and chemical durability, and defect-free surface structures). The key to the unusual properties, and health effects, of asbestiform fibers appears to be in their unusual surface structure. In contrast, non-asbestiform crystals of the same minerals, including the five so called asbestos minerals, do not have these properties and are not carcinogenic.

Jan 1, 1989

By Karl O. Toppel, Jim Flaherty

The desire to minimize gaseous effluent in smelting and maximize gold yields from refractory ore are driving the nonferrous and gold refining industries to demand more and more oxygen. This, coupled with an increasingly competitive marketplace, forces the investigation of alternate methods of oxygen supply. Current progress in both the non-cryogenic and cryogenic fields is making the use of low-purity oxygen much more attractive. The benefits of on-site production are now available to most oxygen users. Historically, these on-site advantages could only be achieved by relatively large plants using high-purity cryogenic technology. The evolution of low-purity cryogenic and non­cryogenic oxygen production has added a new method of delivering on-site production. Specifically, the advent of oxygen Vacuum Swing Adsorption (VSA) technology has brought these benefits to smaller-volume customers by cost-effectively supplying oxygen requirements as low as 20 tons per day, (tpd). Low-purity cryogenic plants have also made an impact on the market, yielding cost reductions for larger-volume customers with oygen requirements greater than 70 tpd. This paper reviews the advantages and disadvantages of current supply methods for users having varying volume, purity and other requirements.

Jan 1, 1993

By Gene E. McClelland, Dirk J. A. van Zyl

5.1 INTRODUCTION Heap leach cyanidation techniques possess considerable potential for exploitation of low-grade ores, small ore bodies, mine strip waste and tailing materials where fine grinding is not necessary for good extraction. For heap leaching to be successfu1, ore must exhibit certain characteristics, as previously discussed in Chapter 1. Primary among the necessary ore characteristics is that the ore must have good permeability after being crushed or treated and stacked into heaps if uniform distribution of the cyanide leach solution is to be achieved. Gold and silver ores containing excessive amounts of clays or fines generated by crushing are some of the most difficult to treat successfully by heap leaching. The presence of excessive amounts of slimes (generally classified as minus 50-micron or 270 Tyler mesh sieve size particles) in the heap leach feed will slow the percolation flow of the leach solution, cause channeling, or produce dormant or unleached areas within the heap. This may result in unreasonably long leaching periods and poor extractions. In extreme cases, the clays or slimes can completely seal the ore heap, causing the leach solution to run off the sides of the heap rather than to penetrate the ore heap. The problem of heap leaching ores containing fines can be aggravated during stacking and preparation of the ore heaps, because natural sorting of coarse and fine material occurs during these steps (Johanson, 1978). This phenomenon results in a concentration of ore fines at the center of individual ore piles and a concomitant concentration of larger rock fragments on the lower slopes and base of the piles. When the individual piles within the heap are leveled off prior to installation of the sprinkling system which delivers the leach solution, additional segregation occurs as the fines sift through the coarser ore particles. The segregation results in localized areas or zones with marked differences in permeability. As a consequence, the leach solutions follow the path of least resistance, percolating downward through the coarse ore regions and bypassing or barely wetting areas that contain large amounts of fines or slimes. Effective utilization of marginal gold and silver resources through heap leach processing requires the development of new methods in order to achieve more uniform size distribution during ore heap preparation and better slime control during leaching.

Jan 1, 1988

The minerals industry contributes to the economic growth, prosperity and quality of life of nations, particularly in areas where there might be limited opportunities for employment in other sectors. However, notwithstanding their economic importance, the minerals extraction and processing industries are considered to have significant impacts on the surrounding environment. In recent years many mines have implemented modern monitoring technology and modelling of the monitored environmental parameters to provide scientifically proven indicators about the state of the environment. The flexibility required by the minerals industry to respond dynamically to a changing natural, social and economic environment has become a major consideration. Whilst the notion of continuous improvement is embodied within most environmental management systems, what is now required is a structured audit trail which tracks the flow of resources through the production process to the ultimate environmental impact associated with their consumption, transformation and disposal. Imperial College is coordinating an EC funded project, which is developing a methodology to minimise the ?full life-cycle? impact of metalliferous mining projects, adopting an integrated approach to production and process design, and the costs involved. In order to develop a life cycle assessment (LCA) system that will incorporate different types of data related to the minerals extraction operations, a data inventory was designed and coded in an object-relational database model. The calculation procedures accounting for the input/output balance of the alternative scenarios for mining production, processing, waste disposal, monitoring, and their financial implications are being programmed into a software system. This paper presents the rational and innovative aspects of this work. The methodology developed for the life cycle database is illustrated for the mining production and gaseous emissions components of the system.

Jan 1, 2003

By Dennis Molvik, Omar Fulton, Chris D. Breeds, Don Gonzales

The Tolt Pipeline No. 2, West Snoqualmie Valley project, is part of a water supply project linking the Tolt reservoir in East King County to the City of Seattle through a nominal 2.13 m (7-ft) inside diameter conveyance. Receipt of the National, 2002Microtunnel Award provided recognition of the many challenges overcome by this project. Baseline conditions revealed in the Geotechnical Documentation included over-consolidated glacial deposits, landslide and alluvial deposits, artesian water, boulders up to 36-in in diameter, logs, heaving sands, and liquefiable soils beneath the river. Schedule constraints associated with setting the shafts in the floodplain of a salmon bearing river and the fickle performance of the river during those times it was not supposed to flood added to the challenge.

Jan 1, 2003

By Odin Wilhelmy

Agriculture in the United States today is becoming more and more a business, rather than a way of life. In the light of this, it behooves the farm-supply industries that provide the American farmer with his tools of production--feed, fertilizer, machinery, and the like--to give even greater attention than they have in the past to meeting the needs of the farmer-businessmen they are serving. Increasing competition among the companies that make up these industries merely accentuates this need for better service. An opportunity for such improved service, not yet fully realized, exists in the fertilizer industry today. That opportunity lies in the increased transportation of fertilizer ingredients by water. However, before the benefits inherent in this increased water movement of fertilizers can be fully realized, certain obstacles must be met and overcome. It is the purpose of this paper to outline the nature and magnitude of this opportunity, to point out some of the roadblocks and the steps that can be, or are being, taken to remove them, and to indicate some of the rewards that would logically stem from success in these efforts.

Jan 1, 1961

By N. Champigny

The geostatistical estimation of the reserves of an ore deposit is highly dependent on the quality and stability of the variograms of the sample grades. Gold deposits commonly show a skewed grade distribution. The few high grades at the tail end of the distribution produce unstable variograms that are difficult to model. If these grades are cut to a lower grade value or removed, more stable variograms are obtained. However, outlier grades may make a deposit economically viable, and their cutting or removal should be treated with caution. To reduce (but not to eliminate) the effect of high grades, a transformation of the raw data can be performed. Most commonly used transformations are: logarithm, gaussian anamorphosis, rank and indicator. Variograms of the transformed grades are resistant to high grades and present a clear structure. The weak point of data transformation appears when grades are estimated by kriging; the estimates are very sensitive to slight variations in the parameters of the back-transformation. More robust variogram estimation procedures can also be used, but often these procedures are not suitable for skewed grade distributions as they are based on an assumption of a contaminated normal distribution. The Porgera gold deposit in Papua New Guinea has a highly skewed grade distribution, with grades ranging from 0.01 to 3500 g/t and a coefficient of variation greater than 5. For the geostatistical estimation of the high grade zone of the deposit, the influence of the high grades was quantified by calculating and comparing the following variograms: raw grades, raw grades with the highest grades removed and transformed grades. The study confirmed that there is no general method for handling high grades in a geostatistical reserve study. Several methods should be tried to quantify the influence of high grades.

Jan 1, 1991

By Ronny J. Sadri

Under contract to the Department of Energy, Fluor Mining & Metals, Inc. and Bonner & Moore Associates developed a group of computer models that can be used to simulate single seam dragline operations. These models have been subsequently modified by Fluor for use in multi-seam dragline mining situations. The single seam model analyzes the digging, spoiling, and walking patterns of draglines to identify possible parameter changes to increase productivity. Parameters such as key-cutting, panel width, digout length, and bench height, etc., are analyzed in this process. The models were tested using data from four operating mines. Field demonstrations were performed to correlate computer optimization results with field data. Productivity was greatly enhanced at one mine site by a change in some of the operating parameters. The multi-seam study has as its objective the development of a broad- based mine planning tool which would be used to identify and quantify the different procedures employed in multi-seam dragline mines to increase their productivity. The major problem identified in multi-seam mining is the sequencing of the different stripping and mining operations. The multi-seam model has the same capabilities as the single seam model. In addition, it models up to four seams with three partings per seam. It allows the operation of several draglines at different levels, and analyzes the effect of ramps, rehandling, and ancillary mining equipment.

Jan 1, 1982

By Gary Jobson

The Mt Todd Gold Mine is owned and operated by Zapopan NL, and is located 300km south of Darwin near the town of Katherine. The crushing plant and heap leach facility, which has operated since November 1993, has recently been expanded to treat 6 Mtpa with 1995 budget gold production reaching 120,000 oz from a head grade of 1.12 git. The process flowsheet and equipment are described, with innovative key features including:

Jan 1, 1995

By T. J. Toy

The topography reconstructed following land disturbance is the foundation for all other reclamation practices. As the manufactured drainage basins, hillslopes, and stream channels approach a steady-state condition, the amount of adjustment of these landforms by geomorphic processes following reclamation decreases. As the adjustment required to establish a steady-state condition decreases, the prospect of reclamation success increases while the prospect of site maintenance decreases. Careful topographic reconstruction is a good investment.

Jan 1, 2002

By G. Chi, M. C. Fuerstenau, R. C. Bradt, A. Ghosh

With increased emphasis on controlled blasting, which is the first and least-costly stage of comminution, ore grindability and plant throughput can be increased by 5% to 10%, and energy savings of up to 10% appear possible. Crushing and grinding efficiencies are presented for ore blasted under regular and adjusted field conditions. An economic analysis of drilling and blasting through crushing and grinding is presented, suggesting that cost savings approaching 10% may be achieved.

Jan 1, 1998

By Harry M. Edenborn, Richard W. Hammack

Experiments were done to determine if a mushroom compost-based sulfate reduction system could be used to treat nickel-contaminated mine waters. Sulfate reduction systems were established in columns containing acid-washed mushroom compost. Simulated mine waters containing 2000 mg/L sulfate and 50 to 1000 mg/L nickel were adjusted to pH 4.5 and pumped through the columns at flow rates between 15 and 25 mL/hr. During the first nine days of operation, virtually all influent nickel was removed in the columns by sorption and ion exchange mechanisms. The nickel removal rate then dropped to 18 to 30 mg Ni/day (7.8 to 12.8 nmol/ g-substrate/day), probably due to low sulfate reduction rates. When sodium lactate was added to the inflow, a sustained and seven-fold increase in the nickel removal rate was observed. Bacterial sulfate reduction rates measured in mushroom compost-based wetlands exposed to coal mine drainage are 2 to 20 times faster than the rates observed in this study. Low sulfate reduction rates in the columns may have been due to the inhibition of microbial activity by high nickel concentrations and the removal of labile organic compounds from the mushroom compost substrate during acid-washing. Results of this study indicate that bacterial sulfate reduction can effectively treat nickel concentrations up to 500 mg/L if labile carbon is nonlimiting.

Jan 1, 1992

By LINDSAY BOTTOMER, Tassos Grammatikopoulos, Massoud Aghamirian, MARK FEDIKOW

A master composite (Master Comp) sample was prepared from three pegmatite zones from the Zoro Dyke D1 for mineralogical analysis and heavy liquid separation (HLS). The mineralogical examination was conducted on a subsample that was crushed to approximately P80 = 600 μm. The sample consists of spodumene (10.5 percent), quartz (29.3 percent), plagioclase (29.0 percent), K-feldspars (21.3 percent), micas (5.1 percent), tourmaline (2.9 percent) and Fe-Mn-phosphates (0.1 percent). Liberation of spodumene (88 percent) and gangue minerals, including quartz (89 percent), feldspars (94 percent) and micas (83 percent), is very good at this P80 . The average lithium (Li) concentration is 3.7 percent in spodumene, 2,196 ppm in micas, 1,001 ppm in tourmaline and 115 ppm in K-feldspars. Spodumene accounts for 96 percent of the total Li in the sample. The mineralogical data indicate the potential to recover spodumene by flotation with minimal Li losses due to other Li carriers. The HLS was conducted on a subsample that was crushed to smaller than 6.4 mm, with the smaller than 600 µm fraction removed from this test. The HLS results indicate it is possible to produce a high-grade lithium concentrate, with close to 6 percent Li2O, after the rejection of iron silicates with magnetic separation.

By V. G. Hill

The term bauxite was first used by O.P.A.P. Dufrenoy in 1845 for an ore which was discovered by Pierre Berthier in 1821 near the village of Les Beaux de Provence near Arles in southern France. His data suggested that this mineral was an alumina hydrate with two molecules of water. However, it was subsequently shown by thermal analysis that the mineral was a fortuitous mixture of the mono-hydrate and the tri-hydrate. Diaspore had been previously discovered in 1801 and gibbsite in 1822. The term was however retained as a rock name. The name of the village was changed to Les Baux around 1885; Sainte Claire Deville suggested that the mineral name should reflect this, and it was changed to bauxite (Bracewell, 1962, Rkgnier, 1988). Mining of bauxite began around 1860 in the Auriol region in the Bouches du Rhine area in the south of France. This ore was transported toMarseilles by carts and was processed in the Salindres plant, which at that time was the only plant producing alumina using the Deville process and aluminum by the chemical process. During that period white bauxite (low iron content) was particularly sought after for the production of aluminum sulfate, refractory bricks, and quick setting cement. Export of bauxite from France began in 1880 and was initially delivered to Chemische Fabrik, Goldschmischen near Breslau, and to Guilini&apos;s Ludwigshafen plant in Germany in 1885. These companies produced alum and aluminum sulfate (RCg- nier, 1988). The next bauxite mining operation was in Antrim County in Northern Ireland in 1873. This was first used for the manufacture of alumina refractory bricks and quick setting cement (Bracewell, 1962). It is important to emphasize that initially almost all of the bauxite which was produced came from France and was mainly used for non-metallurgical purposes. At that time even the production of alumina was mainly for use as a mordant in textile dying. However, with the development of the Hall-Héroult process, the alumina which was available was increasingly used for smelting to aluminum. In spite of this the demand for non-metallurgical bauxite continued to increase and a set of applications were developed. These include refractories, abrasives (including the recently developed proppants), high alumina cements, aluminum chemicals, activated bauxite, and alumina. It became increasingly evident that the high alumina-low alkali raw materials have special advantages. The question however was one of cost benefit. Chin (1989) has pointed out that the non-metallurgical operations have been traditionally grafted on a bauxite/alumina/aluminum industry tree. In this context the non-metallurgical alumina produced was, with few exceptions, regarded as either coproduct or byproduct i.e.: Bauxite Trunk Sector Alumina Trunk Sector Aluminum Trunk Sector

Jan 1, 1994